The ocean covers approximately 70% of Earth's surface, which
means it is the largest environment for living things on Earth. There are
five major ocean habitats: tropical or reef habitat, temperate waters, open
ocean, the deep sea, and polar regions. Most sea life lives in the top 150
meters (500 feet) of the ocean. From the warm, sunlit waters of coral reefs
to the dark, cold waters of the deep sea, the ocean teems with life.

The ocean is an important source of food and other resources.
Since well before recorded history, humans have used the sea as a source of
food. While only 5% of the protein consumed by world populations comes from
the sea, it is still an important contribution to the diet of millions of
the world's inhabitants. In 1996, Americans ate an average of 15 pounds of
seafood per person.

For a very large, one-megabyte image of the chlorophyll
concentration of the ocean in northern hemisphere summer, using all data from
1998-2002, click here: http://bluefin.gsfc.nasa.gov/

Fisheries biology is the study of fish in their natural
environment and their utilization for the needs of humans. Fisheries biologists
are concerned with maintaining the supply of fish or marine life which humans
need. Many factors are involved, but the primary concern is usually with the
marine organism itself.